X-ray Phase Contrast Mask Alignment Using Detector Non-Uniformity
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Solution Overview
Problem
Conventional phase contrast X-ray imaging requires high-powered X-ray beams and precise alignment of masks, which is challenging with conventional X-ray sources and can lead to difficulties in achieving accurate alignment.
Innovation Solution
An apparatus using a conventional laboratory-based X-ray source with a two-dimensional array detector and alignment drives to align masks based on the non-uniformity of detector pixel response, allowing for precise alignment of sample and detector masks to produce optimal phase contrast images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional X-ray sources are used for phase contrast imaging, then the system becomes more accessible and cost-effective, but alignment accuracy of masks deteriorates
Solution Approach 1:
The patent applies preliminary action by performing alignment of the sample mask and detector mask using the non-uniformity pattern of detector pixels before actual phase contrast imaging. The system captures a reference image without a sample, identifies the non-uniformity pattern, and uses this pattern to guide mask positioning. This preliminary alignment step ensures accurate mask-detector alignment is achieved even when using conventional, less precise X-ray sources, thereby resolving the contradiction between source accessibility and alignment precision.
2Measurement precision
If high-powered synchrotron X-ray beams are used, then phase contrast imaging quality improves, but system complexity and cost increase
Solution Approach 1:
The patent applies self-service by utilizing the inherent non-uniformity pattern of the detector pixels themselves as the alignment reference. Instead of requiring external alignment tools or complex reference objects, the system uses the detector's own pixel response variations to guide mask alignment. This self-referential approach enables high-quality phase contrast imaging with conventional X-ray sources while avoiding the complexity of synchrotron facilities.
3Productivity
If masks are aligned using characteristic fringe patterns, then alignment speed improves, but alignment accuracy for conventional sources deteriorates
Solution Approach 1:
The patent applies feedback by using the detected non-uniformity pattern from detector pixels to continuously guide and adjust mask alignment. The system captures images, analyzes the non-uniformity pattern, and uses this information to refine mask positioning iteratively. This feedback mechanism ensures both speed and accuracy in alignment, overcoming the limitations of conventional fringe pattern methods that work well with synchrotrons but fail with conventional X-ray sources.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate alignment of masks for phase contrast imaging using conventional X-ray sources, improving sensitivity and reducing exposure time while maintaining high spatial resolution, thus overcoming the limitations of high-powered sources and alignment complexities.
Implementation Method 1
The method includes measuring a non-uniformity of pixel response of the detector
Implementation Method 2
Phase contrast imaging makes use of the variable phase shifts based on the differences in speed of X-rays in an imaged object
Data Source
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AI summary
A method of aligning masks for phase imaging or phase contrast imaging in X- ray apparatus using a pixel-type X-ray detector makes use of non-idealities of all real detectors. A mask may be provided before the sample to generate beams, adjacent to the pixels of the detector or both. The method includes moving the mask into a plurality of translational position increments and identifying the increment for which the intensity has a maximum or minimum. The identified value of the increment may vary over the pixels of the detector. Alignment positions are selected in which steps in a plot of the increment over the area of the detector are minimised and/or aligned with the rows and columns of pixels.